In addition of the use of BBcode in the popups of your waypoints I added in 'gpxtrackmap.php' a new code so I can open links in a new tab.
If I'm linking to something inside my own website I use the BBCode [url] and [/url]
But if I'm linking to another website I want to open that link in a new tab. So I added an new BBCode with the name [nturl] (newtab url) [/nturl]
After line 1127
"/\[nturl\=(.*?)\](.*?)\[\/nturl\]/is" => "<a href='$1' target='_blank'>$2</a>", // to open links in a new tab
Just for sharing with others who might want to use this.